1. Technical Field of the Invention
This invention is related to digital communication systems, and more particularly to multi-user satellite systems for providing user access to a global packet-switched data network.
2. Background of the Art
The advent of the Internet and the commercial opportunities offered by reaching the millions of potentially new customers which connect thereto have motivated some companies to provide wireless connectivity for those users which cannot use conventional means hardwired means. For example, satellite-based systems provide a mechanism whereby users who are only offered conventional relatively low modem speed access or have no alternative for connecting at all, can now connect to such packet-based systems at higher speeds.
However, inefficient use of resources in multi-user satellite systems results in excessive link margins that drastically reduce system capacity. Typically, the forward link from the satellite to the user is a time-multiplexed data stream that is received by a large number of user terminals. As such, the satellite must be capable of providing service to the user that is under the lowest quality link conditions. Existing satellite communication packet-based systems which offer access to the Internet can transmit digital information to users in unicast, that is, the digital information can be sent to a specific user based upon a unique identification number (ID) assigned to that user, the unique user ID derived via any number of conventional methods. However, existing unicast transmissions still fail to efficiently utilize the available bandwidth by formatting and sending the unicast data under constraints, which anticipate the worst possible reception conditions for any user to reasonably ensure that all users can receive the transmission. This “one-size-fits-all” problem requires satellite systems to operate with link margin requirements that are extremely wasteful to system capacity.
What is needed is a link architecture that allows the link to be customized on a per-user basis to more efficiently utilize channel bandwidth in the communication system.